RU2474069C2 - Method of reducing control signalling in handover situations - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: present invention relates to a method, apparatus and a program for using IP multicast addresses for mobile terminals (6) (user equipment) connected to a communication gateway (1) in a wireless communication network (2). The IP multicast address is used for updating routers (3) in the infrastructure network on where to transport data to the UE when the UE connects to another communication gateway (V), this may be updated from the new communication gateway or from a mobility management entity (5), relieving a network gateway (4) (e.g. a SAE gateway) of control traffic and reducing the risk of bottle necks in the infrastructure network (2).

EFFECT: reducing control signalling during handover.

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Description

FIELD OF THE INVENTION

The invention relates to a solution for managing mobility in a data network and, in particular, to a solution for reducing control signaling in a network with respect to handover situations. The present invention relates to the field of mobility management and user data processing for mobile devices in an active mode in a mobile communication network.

BACKGROUND

Mobility management in a system such as the LTE technology system (E-UTRAN) includes user management in idle mode and in active mode. In idle mode, the mobile device moves in the mobile communication network without sending or receiving data; its position is known to the network approximately, for example, it may be known in which tracking / routing area the mobile device is located, but not its exact cell.

In active mode, the user equipment moves and at the same time sends and receives data (continuously or periodically). The location of the user equipment must be known to the network down to the cell itself and the base station. In a system, especially in a system with small cells, such as an LTE technology system, there may be a problem for user equipment (UE) in active mode in which a lot of signaling will be performed on the network to notify the network of the current location of the user equipment. In a hierarchical network system, for example, in GPRS or Mobitex, an alarm will be made up the network distribution tree to update routing information only in the lower node, common to the new and old cells. Therefore, signaling in the network will be limited. SAE / LTE technology, on the other hand, is defined as a system with a flat IP protocol architecture, and the first common node is also the top node. Tunneling and associated signaling will be very common at the top nodes of the core network.

Therefore, there is a need to identify a solution that performs more efficient signaling to provide mobility for user equipment in active mode for systems with a flat architecture, such as systems technology SAE / LTE.

SUMMARY OF THE INVENTION

An object of the present invention is to provide more efficient mobility management for active mobile devices.

This is achieved in several aspects of the present invention, the first of which provides a method for managing mobility in a wireless communication network supporting Internet Protocol (IP), comprising the steps of:

using IP multicast to transport unicast session data for user equipment entering active mode and connected to a data gateway;

allocate the multicast IP address in the network gateway between the external IP network and the data network (SAE GW gateway);

informing the mobility management entity (MME) the multicast IP address;

informing the data transfer gateway between the user equipment and the infrastructure network of the multicast IP address;

send control messages from the data transfer gateway to the routers in the infrastructure network to notify them that the data transfer gateway must receive multicast data for the allocated multicast IP address;

use the multicast IP address in the network gateway to send user plane data on the downlink to the user equipment;

use IP-enabled routers in the infrastructure network to transport user plane data to the data gateway.

The method may further comprise the step of allowing at least one further data gateway to receive data for the same multicast IP address.

The method may further comprise stages in which:

receiving a signal from the user equipment in the MME that the user equipment has changed the connection to the second data gateway;

report the multicast IP address from the MME to the new data gateway.

The method may further comprise stages in which:

receive in the second data transfer gateway the multicast IP address from the user equipment;

send a control message from the second data gateway to the routers in the infrastructure network to notify them that the data gateway must receive multicast data for the allocated multicast IP address.

The method may further comprise stages in which:

receiving information about at least one data transfer gateway adjacent to a data transfer gateway to which the user equipment is currently connected;

include an adjacent data gateway in receiving data for a dedicated multicast address.

The method may further comprise the step of:

use both the multicast IP address and the source IP of the network gateway to identify the session and multicast data to be received.

In another aspect of the present invention, there is provided an infrastructure network gateway device in an Internet Protocol (IP) -based wireless communication network, comprising:

a processor unit for executing instruction sets;

memory for storing sets of commands and data;

uplink interface;

downlink interface;

moreover, the processor unit is configured to

use multicast over IP to transport unicast session data for user equipment entering active mode and connected to a data transfer gateway;

Highlight multicast IP address

inform the mobility management entity (MME) the multicast IP address;

inform the data transfer gateway between the user equipment and the infrastructure network of the multicast IP address;

Use the multicast IP address to send user plane data on the downlink to user equipment.

In yet another aspect of the present invention, there is provided a mobile terminal in a wireless communication network supporting Internet Protocol (IP), comprising:

processor unit;

memory;

a communication interface configured to interact with a data transmission gateway;

moreover, the mobile terminal is configured to acquire a multicast IP address and communicate this address to the data gateway when the connection from the first data gateway to the second data gateway changes.

In yet another aspect of the present invention, there is provided a wireless communication network with Internet Protocol (IP) support, comprising:

at least one network gateway;

at least one mobility management entity;

at least one data transfer gateway between the mobile terminal and the data network;

moreover, the network is configured to perform the method according to claim 1.

The present invention provides a computer program used in an infrastructure data network device containing command sets for:

using IP multicast to transport unicast session data for user equipment entering active mode and connected to a data gateway;

multicast IP address allocation;

messages to the mobility management entity (MME) multicast IP addresses;

messages between the user equipment and the infrastructure network, the multicast IP address;

using the multicast IP address in the network gateway to send user plane data on the downlink to the user equipment.

In addition, in another aspect of the present invention, there is provided an infrastructure mobility management device in a wireless communication network with Internet Protocol support, comprising:

a processor unit for executing instruction sets;

memory for storing sets of commands and data;

communication interface;

moreover, the processor unit is configured to

receive information about the multicast IP address used for the mobile terminal connected to the data gateway;

Inform the data transfer gateway between the user equipment and the infrastructure network of the multicast IP address.

The solution of the present invention is generally applicable to mobility management for third generation network partnership project systems (3GPP), as well as for systems that are not 3GPP project systems. The benefits are mostly tangible for a system with a flat IP architecture. It applies here to SAE / LTE technology as a flat IP protocol architecture; however, it can be applied to another flat IP protocol architecture.

Additional advantages are the uniform processing of information flows of unicast, two-address and multicast (MBMS) transmissions.

The present invention also provides a dual address mode enabling soft handoff.

The invention provides the effect of freeing network gateways, for example, SAE gateways, from the flow of control information and reduces the risk of bottlenecks in the infrastructure network.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in a non-limiting manner and in more detail with reference to the illustrative embodiments illustrated in the attached drawings.

1 schematically illustrates a network in accordance with the present invention.

Figure 2 schematically illustrates an infrastructure device in accordance with the present invention.

3 schematically illustrates a mobile terminal in accordance with the present invention.

4 schematically illustrates a method during session activation in accordance with the present invention.

5 schematically illustrates a method during a handover in accordance with the present invention; and

6 illustrates a network in accordance with the present invention in a handover situation.

DETAILED DESCRIPTION

1, reference numeral 10 shows a network in accordance with the present invention. The network comprises at least one eNodeB node 1 or any other suitable switching device for connecting the wireless terminal 6 to the infrastructure network, the IP infrastructure backbone network 2, and at least one router or switch 3. System architecture development project gateway 4 (GW) (SAE) is connected to IP backbone network 2 through an S1-U interface. The mobility management entity (MME) 5 is interconnected with a gateway 4 of the SAE GW, but also interconnected with an IP backbone network 2 via an S1-MME interface 9. The IP network is connected to the SAE GW gateway. The eNodeB nodes 1 are configured to communicate wirelessly using any suitable communication protocol with mobile terminals 6 (user equipment (UE)), such as mobile phones, laptop computers, smartphones with a handheld computer (PDA), and other equipment with a wireless interface a communication suitable for the current communication protocol used by the switching device 1.

The invention may be implemented as software in one or more infrastructure devices 200 (as illustrated in FIG. 2) comprising a processor unit 201, at least one memory 202 and an interface 203 for other components for operating the device 200. However, these other components are known specialist and are not included in this description. In addition, the device 200 may have at least one downlink interface 204 and an uplink interface 205 (it should be noted that they can be included in the same physical communication interface, such as an Ethernet connection, etc.) . The memory may comprise a volatile and / or non-volatile type memory, including but not limited to random access memory (RAM), dynamic random access memory (DRAM), read-only memory (ROM), electrically erasable programmable read-only memory device (EEPROM; EEPROM), hard disk, flash memory, etc. The processor unit 201 may comprise any suitable computing device for executing sets of program instructions, including, but not limited to, a microprocessor, a programmable gate array (FPGA), specialized integrated circuits (ASIC), a digital signal processor, etc.

Similarly, FIG. 3 shows a mobile terminal 6, 300 in accordance with the present invention, which operates similarly to infrastructure device 200 with processor unit 301, memory 302, interface 303 with other components of terminal 6, 300, and interface 304 for wireless communication with the infrastructure network 2 (and further), for example, through node 1 of the eNodeB. The memory and processor may be of similar types, as mentioned in relation to the infrastructure device 200.

The communication interfaces 304 and 204 between the terminal 300 and the infrastructure device 200 are designed as wireless interfaces (directly or indirectly using additional infrastructure devices (not shown)) of any suitable type, for example, with support for 2.5G, 3G and higher technologies.

In idle mode, the user equipment 6 moves and its position is known to the MME 5 through the tracking / routing area. In active mode, the user equipment receives and sends data to an endpoint in an external packet data network (PDN), for example, on the Internet. Gateway 4 SAE GW is a gateway to the external network 7 PDN, and the path of the user plane is established between the PDN network and the user equipment through the gateway SAE GW and the current node 1 eNodeB. When the user equipment moves to a new cell, the path must be switched in the SAE GW gateway in order to be able to send downlink data to the user equipment connected to the new eNodeB. Traditionally (for example, in GPRS technology) this is done when managing a session by maintaining the context of the packet data protocol (PDP) and the tunnel using the GPRS tunneling protocol (GTP) through the network (NW). However, there is a problem with this solution; when the cells are small and the architecture is flat, extensive signaling to the SAE GW gateway will be performed to update all tunnels for each user equipment to the desired eNodeB.

In this solution, IP multicast is used as a transport mechanism between the GW SAE gateway 4 and the eNodeB 1 to transport the user plane for user equipment 6 in active mode, i.e., IP multicast is used as the transport protocol for unicast data . User packets in unicast mode will be encapsulated and transported on the backbone network using multicast transport over IP. The GTP user plane protocol will not be used. The procedure will be that when the user equipment enters active mode, it tells the gateway 4 SAE GW or object 5 MME to activate the user plane. The MME or Gateway SAE GW will allocate a multicast IP address; alternatively, the multicast IP address is requested and received from the selected SAE GW gateway. When using Source Specified Multicast (SSM) for signaling, the source address of the SAE GW gateway will also be provided for the channel, and it will be used by the eNodeB in the IGMP Join message. Using the SSM extension for IP multicast (RFC 4607), it will be possible to more quickly establish an IP multicast path between the SAE GW and the eNodeB, which is important for mobility when moving between cells. An activation message including the multicast IP address is sent to the SAE GW gateway (or known to the SAE GW gateway if it is an entity providing the multicast IP address) and the eNodeB (alternatively to user equipment). The SAE GW gateway will send the user equipment downlink data to the assigned multicast IP address. The eNodeB must receive data sent to the multicast IP address, and therefore sends an IGMP Join message (or a similar control message to notify the network that it wants to belong to a given multicast group, for example, a membership report message used in IGMPv3) backbone network. IP Trunk 2 supports multicast because routers 3 are compatible with IP multicast. Routers will receive the IGMP Join message and forward it so that all packets sent to the specified multicast IP address on the trunk network will be delivered to the eNodeB that is connected. The SAE GW gateway will send the downlink data to the multicast IP address without actually knowing the location of the user equipment and at which eNodeB the user plane ends.

When the user equipment moves to the new eNodeB, the user equipment tells the network, for example, the MME, the new location (eNodeB), and the MME sends the multicast IP address of the user equipment session user plane to the new eNodeB, which is now connected to the group IP transmissions by sending an IGMP Join message to the backbone network. The backbone network creates a new transmission path so that the information flow is now sent to the new eNodeB, and the user equipment can receive session data. It should be noted that there is no signaling to the SAE GW gateway, which does not know the location of the user equipment, but should only provide information flow to the backbone network that supports multicast over IP. An alternative method would be for the MME to inform the user equipment of the multicast IP address upon activation. In this case, when the user equipment moves to the new eNodeB, the user equipment can initiate the IGN protocol to be executed by the new eNodeB. The user equipment reports the multicast IP address to the new eNodeB, and the new eNodeB performs the IGMP join to the backbone network. The MME may or may not be informed of a cell change.

An additional possibility when applying the proposed method is to facilitate efficient handover (HO) by communicating to the cells surrounding the cell in which the user equipment is currently located so that they also join the multicast transport over IP. Then, if the user equipment moves to an adjacent cell, the new eNodeB already has a downlink information flow, and it can be delivered to the user equipment without interruption. This will be discussed in more detail with respect to FIG. 6 later in this document.

It should be noted that using the extension (IETF documents RFC 4607, 4604, 4608) for multicast with a given source (SSM) for multicast over IP, the source IP address is used for routing multicast over IP. In this case, routing and creating routing tables are more efficient. Also, the source address will always be available in the destination, that is, in the eNodeB node, and the eNodeB node will also use the source address to send the uplink information flow for the session in question so that the uplink goes to the desired SAE GW gateway, which will act as a reference point for the information flow of downlink and uplink.

The mobility support described here is very general and can also be used for mobility outside of the 3GPP project, as well as in any network that supports multicast transmission over IP in accordance with the RFCs for multicast transmission with a given source (SSM) over IP.

For the SAE GW gateway, the processing of the unicast downlink information stream and the multicast downlink information stream (MBMS) will be the same and will mainly differ in the source of the information stream (BM-SC center for the MBMS information stream through the SGmb and SGi interfaces and external / internal PDN via SGi interface for unicast information flow). GTP is not used, and the multicast IP address is used instead of the tunnel endpoint identifiers (TEIDs) of the GTP protocol.

An exemplary session activation method will be described below with reference to FIG. 4:

401. The user equipment joins the network (registered in the object MME1 and authenticated, etc.). The user equipment wants to activate a data transfer session (equivalent to performing PDP context activation in the GPRS system) and sends an activation message to the MME.

402. An MME allocates a channel with the correct channel characteristics, such as quality of service (QoS), mode, etc. (using some method that is not of interest in the context discussed here). The MME selects the SAE GW gateway (for example, using APN), and also assigns a transport channel between the GW SAE gateway and the eNodeB (equivalent to the GTP tunnel used in the GPRS system), i.e. the MME assigns the multicast IP address, which the SAE GW gateway should use to send downlink user plane data to the eNodeB for this user plane transport channel. Assignment of a multicast IP address can alternatively be performed at the SAE GW gateway as part of the procedure or upon request from the MME.

403. The MME sends the channel parameters, including the multicast IP address, to the SAE GW gateway. The SAE GW Gateway creates a session context for the user equipment.

404. The MME sends the channel parameters to the eNodeB, including the multicast IP address. The eNodeB node creates a context for the session for the user equipment.

405. The eNodeB sends an Join message to the IGMP backbone network supporting IP multicast, which creates a transport path between the SAE GW and the eNodeB.

406. The user equipment can start sending and receiving data along the user plane path through the eNodeB and the SAE GW to the external PDN, such as the Internet, and from it. The SAE GW gateway does not have to worry about the location of the user equipment, but only sends downlink data to the trunk network that supports multicast over IP, which will ensure the delivery of data to the desired eNodeB.

Below, with reference to FIG. 5, an illustrative method for processing a handover to a new cell in an active mode is described:

501. The user equipment is in active mode, has a current user plane session, moves to a new cell, and is accessible through a new eNodeB.

502. A user equipment reports a cell change to an MME.

503. The MME indicates the multicast IP address for the new eNodeB, which is used by the SAE GW to transport the downlink user plane data stream. It also indicates the source IP address that the eNodeB will use when joining (IGMP) if multicast with a specified source (SSM) is used and for sending the upstream user plane information stream for the session for this user equipment.

504. The new eNodeB sends an IGMP Join message to the backbone network to join the session transport and start receiving the information flow for this user equipment.

505. The IP multicast network creates a distribution tree for the downlink data path for this session (that is, for the multicast IP address).

506. The new eNodeB starts receiving downlink data that is sent to the user equipment.

507. The old eNodeB is notified (or session time out), and the old eNodeB sends an IGMP Leave message to stop the payload from being delivered to the old eNodeB.

It should be noted that in the handover procedure, there is no signaling to the SAE GW gateway. The SAE GW gateway does not know the location of the user equipment, but will only send downlink data to a trunk network that supports multicast over IP, which will route packets to the desired eNodeB.

It should be noted that if an alternative method is used in which the transport channel information (i.e., the IP multicast transport address) is sent to the user equipment, the above diagram is simplified so that the MME is not used and the new eNodeB is directly informed by the user equipment about the multicast IP address.

6 illustrates a network handover case in accordance with the present invention in which data from an application server 601 must be downlink to user equipment 6. However, during this process, user equipment 6 moves to a new location and thus connects to another node 1 'eNodeB. Then the data should be redirected to the new node 1 'eNodeB. Data is sent to gateway 4 of the SAE GW and there it is sent to the multicast address specified for user equipment 1. In this case, it will be sent to the direction 602 of the last known eNodeB node 1 through routers 606 and 607 with an end connection 603 to eNodeB node 1. However, router 606 was informed that data at the multicast address should now be routed (also) to the new 1 'eNodeB, to which the user equipment is now connected. When the user equipment has moved, the new node 1 'eNodeB has informed (using appropriate multicast control messages) the upstream routers 608 and 606 about the new situation, and therefore, the router 606 can also send data along the new path 604. When the user equipment has left the old eNodeB node and is completely disconnected from it, the old eNodeB node informs (using appropriate multicast control messages) the routes located upstream teasers 607 and 606 about the new situation, and therefore, router 606 may stop sending data along path 603.

In one embodiment of the present invention, the upstream router 606 at an appropriate level may be informed that there is some chance that the user equipment 1 will change the eNodeB node in the near future, as well as which node (s) of the eNodeB are likely to will be connected (s) to user equipment. In this case, it is possible to send data in two (or more) directions simultaneously, the so-called two-address solution: in the direction in which the user equipment is currently located and in the direction to the node 1 ′ eNodeB, with which the user equipment is likely to connect to in the nearest future. Thus, the movement of user equipment 6 is predicted, and the risk of data loss is reduced. The same multicast solution can be used when it is actually known that the user equipment is in the process of moving from one eNodeB node 1 to another eNodeB node 1 'to provide efficient soft handoff using the multicast solution of the present invention.

Multicast IP addresses can generally be allocated in the range from 224.0.0.0 to 239.255.255.255, and the sub-band allocated for using multicast with a given source is a range from 232.0.0.0 to 232.255.255.255 (232/8) . For IPv6, this corresponds to the FF3x :: / 32 range. Some addresses in the range may be reserved, but up to 16 million addresses may be available for each source address when multicast with a given source is used according to RFC 4607, 4604 and 4608. IP multicast address range with a specified source (SSM) can be reused for each SAE GW gateway. This means that the solution is scalable, and any number of sessions can only be supported by adding additional SAE GW gateways, when each SAE GW gateway has its own unique IP address (that is, the source address for SSM transmission).

Some of the effects of this invention are effective signaling and simplified mobility management with a flat mobile network architecture that supports multicast over IP.

It should be noted that the word "contains", "comprising" does not exclude the presence of other elements or steps other than those listed, and the use of the name of the element in the singular does not exclude the presence of many such elements. It should also be noted that any reference signs do not limit the scope of the claimed claims, that the invention can be at least partially implemented both through hardware and software, and that several "means" can be represented by the same element hardware equipment.

Mentioned and described above embodiments are given only as examples and should not limit the present invention. Other solutions, uses, objectives and functions within the scope of the invention set forth in the claims below should be apparent to those skilled in the art.

DEFINITIONS AND ABBREVIATIONS

BS Base Station

DL Downlink

eNodeB Node B E-UTRAN

E-UTRAN UMTS Advanced Terrestrial Wireless Access Network

GPRS Public Wireless Packet System

GTP GPRS Tunneling Protocol

GW Gateway

IP Internet Routing Protocol

LTE Long-Term Wireless Data Development Project

MAC Media Access Control

MBMS Media Broadcast and Multicast Service

MC Multicast

MCCH Multicast Control Channel

MCH Multicast Channel

MME Mobility Management Object

MS Mobile Station

NodeB UTRAN Base Station

PDN Packet Data Networks

PDU Protocol Data Unit

RNC Wireless Network Controller

SAE System Architecture Development Project

SSM Multicast with a given source

TEID Tunnel Endpoint Identifier

UE User Equipment

UL Uplink

UL-SCH Uplink Shared Channel

UMTS Universal Mobile Communications System

UP User Plane

UPE User Plane Object

U-plane User plane

UTRA UMTS Terrestrial Wireless Access

UTRAN UMTS Wireless Terrestrial Network

VoIP Voice over IP

WCDMA Code Division Broadband Multiple Access

WLAN Wireless LAN

Claims (10)

1. A method for managing mobility in a wireless communication network with Internet Protocol (IP) support, comprising the steps of:
using IP multicast to transport unicast session data for user equipment (6) (UE) entering active mode and connected to a data transfer gateway (1);
allocating a multicast IP address in a network gateway (4) (SAE GW) between the external IP network and the data network;
informing the mobility management entity (5) of the multicast IP address;
informing the gateway (1) of the data transfer between the user equipment and the infrastructure network (2) the multicast IP address;
send a control message from the data transfer gateway to the routers (3) in the infrastructure network to notify them that the data transfer gateway must receive multicast data for the allocated multicast IP address;
use the multicast IP address in the network gateway to send user plane data on the downlink to the user equipment;
use IP-enabled routers in the infrastructure network to transport user plane data to the data gateway. 2. The method according to claim 1, further comprising the step of allowing at least one further data gateway to receive data for the same multicast IP address. 3. The method according to claim 2, further comprising stages in which:
receive a signal from the user equipment in the object MME about
that the user equipment has changed the connection to a second data gateway (1 ');
report the multicast IP address from the MME to the new data transfer gateway. 4. The method according to claim 2, further comprising stages in which:
receive in the second data gateway the IP address of the multicast from the user equipment;
send a control message from the second data gateway to the routers in the infrastructure network to notify them that the data gateway must receive multicast data for the allocated multicast IP address. 5. The method according to claim 2, further comprising stages in which:
receiving information about at least one data transfer gateway adjacent to the data transfer gateway to which the user equipment is currently connected;
include an adjacent data gateway in receiving data for a dedicated multicast address. 6. The method according to any one of claims 2-5, further comprising the step of:
use both the multicast IP address and the source IP of the network gateway to identify the session and multicast data to be received. 7. A device (4) of an infrastructure network gateway in a network (2) of wireless communication with Internet Protocol (IP) support, comprising:
a processor unit (201) for executing instruction sets;
a memory (202) for storing sets of instructions and data;
uplink interface (205);
downlink interface (204);
moreover, the processor unit is configured to
use IP multicast to transport unicast session data for user equipment (6) (UE) that is in active mode and connected to a data transfer gateway (1);
Highlight multicast IP address
inform the mobility management entity (5) of the multicast IP address;
inform the data transfer gateway between the user equipment and the infrastructure network of the multicast IP address;
Use the multicast IP address to send user plane data on the downlink to user equipment. 8. A mobile terminal (6) in a wireless communication network supporting Internet Protocol (IP), comprising:
a processor unit (301);
memory (302);
a communication interface (304) configured to interact with a data transmission gateway (1);
moreover, the mobile terminal is configured to acquire a multicast IP address and communicate this address to the data transfer gateway when the connection changes from the first data transfer gateway (1) to the second data transfer gateway (1 '). 9. Network (2) wireless communication with support for Internet Protocol (IP), comprising:
at least one network gateway (4);
at least one mobility management entity (5);
at least one data transfer gateway (1) between the mobile terminal (6) and the data network (2);
moreover, the network is configured to perform the method in accordance with claim 1. 10. An infrastructure device (5) for managing mobility in a network (2) wireless communications with support for Internet Protocol (IP), containing:
a processor unit for executing instruction sets;
memory for storing sets of commands and data;
communication interface;
moreover, the processor unit is configured to
receive information about the multicast IP address used for the mobile terminal connected to the data gateway;
Inform the data transfer gateway between the user equipment and the infrastructure network of the multicast IP address.

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